The invention relates to a new method of inhibiting the growth of microorganisms in aqueous systems. More specifically, it relates to a method of using 2,2,3-trihalopropionaldehydes to inhibit the growth of microorganisms in aqueous systems.
Biofouling is a problem which attends many aqueous systems. For example, lagoons, lakes, ponds, pools, industrial wash water, cooling water and pulp and paper mill water all possess conditions which are conducive to the growth and reproduction of slime-forming microorganisms. In both once-through and recirculating cooling, for example, biofouling, such as slime production and algal matting, by microorganisms is an extensive and constant problem.
Airborne organisms are readily entrained in the water of cooling towers and find this warm medium an ideal environment for growth and multiplication. In the case of cooling towers, aerobic and heliotropic organisms flourish on the tower proper while other organisms colonize and grow in such areas as the tower sump, piping and passages of the cooling system. Such organisms produce a slime which deteriorates the tower structure in the case of wooden towers. In addition, the deposition of slime on metal surfaces promotes corrosion. Furthermore, slime carried through the cooling system plugs and fouls lines, valves, strainers, etc., and deposits on heat exchange surfaces. In the latter case, the impedence of heat transfer can greatly reduce the efficiency of the cooling system.
In pulp and paper mill systems, slime formed by microorganisms is also frequently and, in fact, commonly encountered. Fouling or plugging by slime also occurs in the case of pulp and paper mill systems. Microbial attack by either bacteria or fungi, or both, causes the loss of useful properties, foul odors, slime formation, slime spots in paper, reduced strength of paper, production down-time, and the possibility of skin infections in persons handling these materials.
As a result, extensive use is made of biocides in cooling water and pulp and paper mill systems. Materials which have enjoyed widespread use in such applications include chlorine, organo-mercurials, chlorinated phenols, organo-bromines and various organo-sulfur compounds. Other materials used as antimicrobials, especially as slimicides are halocyanoamides, in particular, 2,2-dibromonitrilopropionamide (DBNPA). See Nolan et al., U.S. Pat. No. 2,419,888; Schmidt et al., U.S. Pat. No. 3,493,658; Wolf, U.S. Pat. No. 3,649,166; and CIBA S.A., Belgian Pat. No. 668,336.
Another known antimicrobial compound is 2,3-dibromopropionaldehyde (see Schwerdle, U.S. Pat. No. 3,582,463, June 1, 1971, incorporated herein by reference). Both 2,3-dibromopropionaldehyde and 2,2-dibromonitrilopropionamide (DBNPA) are relatively unstable compounds which have a tendency to decompose in storage and in transit. The use of stabilizers to prevent this decomposition is often required. See Schwerdle, U.S. Pat. No. 3,582,463 and Burk et al., U.S. Pat. No. 4,163,798, Aug. 7, 1979 (incorporated herein by reference). These compounds are relatively ineffective in basic aqueous systems.
An antimicrobial compound which is relatively stable and is effective under basic conditions is desirable. Such an antimicrobial compound has been discovered.